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Similan Islands are located just 84 km northwest of the bustling crowds of Phuket. Koh Similan is one of the best-known island groups in the Andaman Sea, largely because of the wonders that wait beneath the clear blue waters that surround it. Generally counted among the 10 most interesting dive areas in the world, this little archipelago has also become a favourite destination for yachts and tour boats.

"Similan" is derived from the Malay sembilan, and means "nine". Each of the Similan Islands has a number as well as a name. These are, running from north to south: Koh Ba Ngu (No. 9), Similan (No. 8), Payu (No. 7), Miang (No. 4, No. 5 and, in some opinion, No. 6), Payan (No. 3), Payang (No. 2), and Hu Yong (No. 1). Hin Pousar, or "Elephant Head Rock", is alternatively designated No. 6 by some. Koh Bon, lying 17 nautical miles north of Ba Ngu, is part of the Similan National Park and may be granted honorary status as No. 10.

Please note that the Similan islands are officially open to the public from 15 October until 15 May, but dates may vary each year.

Similan Islands Highlights

What is it that makes these islands so attractive? The Similans aren't as dramatically scenic as the limestone islands of Krabi or Phang Nga Bay, which many people have come to associate with the Andaman Sea. Instead, you find low-lying formations covered with thick forest.

Ironwood and gum trees are among the larger trees, while jackfruit, rattan and bamboo form part of the denser undergrowth. The islands are home to crab-eating monkeys, dusky langurs, squirrels, bats, lizards and a good variety of birds (though the monkeys are shy and rarely seen by the casual observer).

But the most striking feature of these islands, at first glance, are the huge boulders that litter the western and southern shores on several of the islands. Another highlight, as the visitor soon discovers, are the white coral-sand beaches, splendidly picturesque and often deserted.

The most interesting sights, however, are to be found beneath the waves. Some of the most spectacular coral growths in the world can be found here - and the same boulders that scatter the shores have turned the waters around the Similans into an adventure playground for divers.

Topographical Treats

At various times in the past - with sea levels fluctuating by as much as 150m with the advance and retreat of the polar ice-caps - these islands have been under water, battered by storms, covered with marine growths, visited by creatures long extinct.

Think of that when you clamber up the trail to Sailing Boat Rock, on Island No. 8, for example. As you squeeze through the crevices and archways, imagine them covered with colourful corals, sponges and algae. Where today you find birds and butterflies and squirrels, at one time dense schools, bright streams of fish instead commuted this way and that, with bigger fish and marine dinosaurs cruising through on the hunt.

A variety of forces have given shape to these islands. To begin with, the Similans were intrusions, upwellings of hot magma that found their way through weak spots in the Earth's crust 100-150 million years ago, working their way through thick layers of sedimentary rock already laid down at least 100 million years earlier still. Then, unimaginably powerful movements in the crust cracked the granite substratum into blocks, preparing the way for experiments in sculptural form by wind and wave.

Similan Islands

Today, piles of curious stones, some of them as big as houses, lie as though collected and later abandoned in careless heaps by some ancient race of beachcombing giants. Even Sailing Boat Rock, the distinctive formation teetering high above the cove on Koh Similan (Island No.8), has been shaped in this way.

And boulders just like these spill in jumbled piles down beneath the surface of the sea to 35m and beyond, where submarine peaks, canyons, caves and passageways provide scuba divers with some of the most interesting submarine prospects in the world. (On the west side of the islands, currents have kept the formations clear of sand; on the coral-covered sandy slopes of the east side, the boulders have been largely buried.)

Similan Islands Wonders

Underwater, meanwhile, all sorts of marine creatures have helped establish the reefs and the sandy beaches. When you climb up to Sailing Boat Rock, consider the brilliant white sand below.

This beach is in large part a product of diligent scraping and nibbling away by organisms such as the parrotfish - an average individual of which species may excrete more than 16 kilos of sand in the course of a year's lunching on hard corals. And there's plenty here to eat.

The conditions for coral growth are ideal, with a minimum prevailing sea temperature of about 28oC and exceptionally clear waters. More than 200 species of hard coral alone have so far been identified in this area, while these islands have the greatest profusion of reef fish in Thai waters.

In fact, in terms of both marine life and bottom topography, there's more variety than you'll find in most other dive destinations around the world. The Similan Islands has almost everything - coral walls (if we count Koh Bon, to the north, as one of the Similans), big rocks, huge sea fans and barrel sponges, caves, swim-throughs, and plenty of shallows for snorkelling as well. For, although the fringing waters around the islands average from 30-45m dropping down to 70-80m between islands, you'll find coral gardens in as little as six to seven metres.

A Sailor's Fancy

It's best known as a diving and snorkelling destination, but the Similans' scenic moorings are also becoming increasingly popular with the sailing fraternity. Every year more yachts come to cruise the Similans during the northeast monsoon (November-May, with December-February the peak of the high season), drawn by the lovely anchorages, the beaches and forests, the clear waters and teeming marine life.

Bareboat sailing charters and sailing-diving cruises may be booked from Phuket. If you are on a yacht that doesn't have scuba gear or a compressor, you can always hire what you need from the diveboats that come out from Phuket on a regular basis. Aside from sailing and diving, more and more dayboats are coming out from Phuket and Phang Nga during the high season, bringing with them crowds of sightseers, picnickers, and snorkellers. And Koh Similan National Park has added to its many attractions its role as a stopover on the way to yet newer and more distant undersea frontiers and sailing destinations - areas such as the Andaman Islands, the Invisible Bank and, when they reopen to sport diving, the Burma Banks.

Getting to the Similans

There is no regular boat service for visitors to the island, and during the low season months of May-October boats may stop running altogether depending on the weather conditions. Thap Lamu Pier, in the Thai Muang district of Phang Nga province, is the nearest launching point to the Similans, with boat trips taking about 3 hours.

More adventurous travellers may try to hitch a ride with some of the local boats heading out there - just be sure to allow lots of time since there's no guarantee that there will be a ride back on any given day. Note that a park entry fee of 200 baht is charged.

Daytrips from Phuket and Khao Lak are also possible, with travel time of 45 minutes to 3 hours depending on the boat used. A popular way to go, especially for divers and game fishers, is by joining a liveaboard boat trip from Phuket, which usually run for 4 days. There are many Phuket-based liveaboard operations offering varying levels of luxury and facilities.

Similan Islands

Opening Hours: open to the public from 15 October until 15 May, but dates may vary each year.

We try to provide free information that is as up-to-date and accurate as possible. However, if you are planning to travel it's a good idea to double check specific dates and information to avoid surprises.